Data-signaling apparatus for well drilling tools

ABSTRACT

In the preferred embodiment of the invention disclosed herein, a well tool having new and improved data-signaling apparatus and carrying a drill bit on its lower end is dependently coupled from a drill string and lowered into a borehole being excavated. During the drilling operation, measurements are successively made of selected borehole conditions, formation properties, or the like, which are converted by the data-signaling apparatus into coded electrical signals for repetitively opening and closing a valve including a valve member and a movable valve seat operatively arranged on the tool for selectively interrupting and then resuming the flow of the drilling fluid being circulated through the drill string. In this manner, the valve functions to produce a series of encoded pressure pulses in the drilling fluid which are representative of the measurements being obtained. These pressure pulses are transmitted through the drilling fluid to the surface where they are sensed and converted into meaningful indications of the measurements.

United States Patent 1 Cubberly, Jr.

n11 3,736,558 1 May 29, 1973 [54] DATA-SIGNALING APPARATUS FOR WELLDRILLING TOOLS [75] Inventor: Walter E. Cubberly, Jr., Houston,

Tex.

[73] Assignee: Schlumberger Technology Corporation, New York, N.Y.

[22] Filed: July 30, 1970 [21] Appl. No.: 59,393

[52] U.S. Cl. ..340/l8 LD, 340/18 NC [51] Int. Cl. ..G01v 1/14 [58]Field of Search ..340/18 LD [56] References Cited UNITED STATES PATENTS2,700,] 31 1/1955 Otis et a1. ..340/18 LD 3,255,353 6/1966Scherbatskoy.... ....340/18 LD 2,787,759 4/1957 Arps ....340/18 LD3,408,561 10/1968 Repwine et al.... ....340/18 LD 3,333,239 7/1967Silverman ....340/l8 LD 2,352,833 7/1944 Hassler ..340/l8 LD PrimaryExaminerBenjamin A. Borchelt Assistant Examiner-N. MoskowitzAttorney-Ernest R. Archambeau, Jr., Stewart F. Moore, David L. Moseley,Edward M. Roney and William R. Sherman [57] ABSTRACT In the preferredembodiment of the invention disclosed herein, a well tool having new andimproved data-signaling apparatus and carrying a drill bit on its lowerend is dependently coupled from a drill string and lowered into aborehole being excavated. During the drilling operation, measurementsare successively made of selected borehole conditions, formationproperties, or the like, which are converted by the datasignalingapparatus into coded electrical signals for repetitively opening andclosing a valve including a valve member and a movable valve seatoperatively arranged on the tool for selectively interrupting and thenresuming the flow of the drilling fluid being circulated through thedrill string. In this manner, the valve functions to produce a series ofencoded pressure pulses in the drilling fluid which are representativeof the measurements being obtained. These pressure pulses aretransmitted through the drilling fluid to the surface where they aresensed and converted into meaningful indications of the measurements.

19 Claims, 6 Drawing Figures 29 sun 28 GENERATOR PATENTEDHAYZQ I973SHEET 1 BF 3 20 SIGNALER 79 ENCODER 17 MEASURING DEVICE 27 SIGNALMEASURER --28 GENERATOR E m V E D Walter E Cubberly Jr INVENTOR FIG. 2

AT TORNE Y PATENTEHMAYZQ I975 SHEET 2 BF 3 4 g G U a d 9 3 I 3 3 F 3 5 74 M 4 w 4 R d 6 f P a d 1, A w X m I. w H M x\ I A m x L m V V M AW 4 vi 1| H l a i m z v M 7 6 2 /4 4 Walter E. Cubberly J1."

ATTORNEY PATENTEDMM 29 I975 SHEET 3 BF 3 III OOQOOGh FIG. 5

Walter E. Cubberly Jr INVENTOR /zfldmzajl A T TORNE Y DATA-SIGNALINGAPPARATUS FOR WELL DRILLING TOOLS Those skilled in the art have, ofcourse, long recognized the benefits of obtaining various measurementsat the bottom of a borehole during the course of a drilling operation.For instance, such information as the weight on the drill bit, the drillstring torque, the inclination and the azimuthal direction of theborehole, bottom hole pressures and temperatures as well as variouscharacteristics of the formations being penetrated are all measurementsof significant interest.

Various proposals have, of course, been made heretofore fro transmittingsuch measurements from the bottom of a borehole to the surface. Of themany different tools proposed, perhaps the most promising of all utilizea condition-responsive valve for selectively interrupting the flow ofthe circulating drilling fluid in a predetermined coded sequencerepresentative of the measurements to produce a series of momentarypressure surges which are successively transmitted through the drillingfluid to the surface for detection by appropriate sensing devices. Theseproposed tools have, therefore, generally employed a typicalsolenoidoperated valve which is coupled to one or more condition-sensingdevices by means of appropriate electronic circuitry operativelyarranged for opening and closing the valve in accordance with this codedsequence.

For various reasons, however, these prior proposals have generally beenconsidered to be unacceptable for commercial drilling operations. Forinstance, since the signaling valves in such prior tools havecustomarily been directly operated by solenoids, the mechanical forcesrequired just for operating these valves are so large that the powerrequirements for these solenoids become excessive in even relativelyshallow wells. Moreover, by virtue of their substantial powerrequirements, the physical size of such solenoids make them impracticalfor the usual sizes of drilling tools.

Accordingly, it is an object of the present invention to provide new andimproved data-signaling apparatus for use with well-drilling tools andwhich is specially adapted for rapidly transmitting downholemeasurements to the surface with minimum electrical requirements.

This and other objects of the present invention are attained byproviding a well tool adapted to be connected in a drill string having adrill bit dependently coupled thereto for excavating a borehole as adrilling fluid is circulated through the drill string and a fluidpassage arranged in the tool. Data-signaling means are arranged on thetool and include condition-measuring means which are coupled tomeasurement-encoding means adapted for producing coded electricalsignals indicative of one or more selected downhole conditions which maybe experienced during the course of a drilling operation. To generatedistinctive pressure pulses in the circulating drilling fluidrepresentative of such measurements, the measurement-encoding meansoperatively drive pressure-signaling means arranged on the tool andincluding valve means which are releasably retained from movement to apassage-closing position by electrically responsive latch means adaptedfor selective operation in response to the electrical signals producedby the measurement-encoding means for initiating the closure of thevalve means. Pressureresponsive means are operatively associated withthe valve means and adapted for utilizing the circulating drilling fluidas a motive force to positively operate the valve means as well as toenergize biasing means operatively arranged for returning the valvemeans to a passage-opening position to await the next electrical signal.

The novel features of the present invention are set forth withparticularity in the appended claims. The invention, together withfurther objects and advantages thereof, may be best understood by way ofthe following description of exemplary apparatus employing theprinciples of the invention as illustrated in the accompanying drawings,in which:

FIG. 1 shows a well tool arranged in accordance with the presentinvention as it will appear while coupled in a drillstring during thecourse of a typical drilling operation; 1

FIG. 2 is a schematic representation of a preferred embodiment of thetool shown in FIG. 1; and

FIGS. 3-6 schematically depict certain successive operating positions ofa preferred embodiment of datasignaling apparatus incorporating theprinciples of the present invention.

Turning now to FIG. 1, a new and improved well tool 10 arranged inaccordance with the present invention is depicted coupled in a typicaldrill string 11 having a rotary drill bit 12 dependently coupled theretoand adapted for excavating a borehole 13 through various earthformations as at 14. As the drill string 11 is rotated by a typicaldrilling rig (not shown) at the surface, substantial volumes of adrilling fluid or co-called mud are continuously pumped downwardlythrough the tubular drill string and discharged from the drill bit 12 tocool the bit as well as to carry earth borings removed by the bit to thesurface as the mud is returned upwardly along the borehole 13 exteriorof the drill string. As is typical, the mud stream is circulated byemploying one or more high-pressure mud pumps (not shown) whichcontinuously draw the fluid from a storage pit or vessel for subsequentrecirculation by the mud pumps. It will be appreciated, therefore, thatthe constantly circulating mud stream flowing through the drill string11 serves as a transmission media that is well suited for transmittingpressure surges or pulses to the surface.

In accordance with'the principles of the present invention,data-signaling means 15 are arranged on the well tool 10 and includecondition-measuring means 16 such as one or more condition-responsivedevices, as at 17 and 18, which are coupled to an appropriatemeasurement encoder l9 operatively arranged to produce a series of codedelectrical signals that are representative of the measurements beingobtained by the condition-responsive devices. Pressure-signaling means20 coupled to the encoder 19 are operatively arranged to respond tothese coded signals for selectively generating a corresponding series ofpressure pulses in the circulating fluid by momentarily and rapidlyinterrupting the flow of the drilling fluid through the drill string 11.It will be appreciated, of course, that these transitory pressure pulsesor surges will be similar to those caused by a so-called water hammer.Thus, these pressure waves will be transmitted to the surface by way ofthe mud stream flowing within the drill string 1 l and at the speed ofsound in the particular drilling fluid. Accordingly, as willsubsequently be explained in greater detail, the pressure-signalingmeans 20 produce these pressure pulses to provide encodedrepresentations or data indicative of the one or more downholeconditions sensed by the condition-measuring devices 17 and 18. Thisdata is, in turn, successively transmitted to the surface in the form ofthese pressure pulses for detection and conversion into meaningfulindications or records by suitable surface-located pressure-transducingapparatus 21 such as those disclosed in either US. Pat. No.

3,488,629 or a copending application Ser. No. US. Pat. No. 3,555,504.

Turning now to FIG. 2, a schematic view is shown of the new and improvedwell tool just prior to the production of a pressure surge or pulsewhich is to be transmitted to the surface by way of the drilling fluidbeing circulated through the drill string 11. As illustrated, the welltool 10 is comprised of an elongated tubular member 22 that is coaxiallyarranged within a thick-wall tubular housing 23 which is tandemlycoupled in the drill string 11 just above the drill bit 12.

Although the inner member 22 could just as well be releasably secured tothe outer housing 23, it is preferred to permanently mount the innermember within the housing as illustrated. In this manner, by securingthe lower end of the inner member 22 to the outer housing 23 as bythreads at 24, an annular space 25 will be defined between the interiorwall of the housing and the exterior of the inner member.

Although a self-contained power supply could be employed, it ispreferred to utilize the flowing mud stream as a motivating source forgenerating electrical power for operation of the new and improved welltool 10. Accordingly, in the preferred manner of accomplishing this, areaction turbine 26 is journalled, as by a bearing 27, to the upper endof the inner member 22 and operatively arranged to be rotatively drivenby the downwardly flowing drilling fluid for driving a generator 28coupled to the turbine by an elongated shaft 29. Thus, as the mud streamflows through the turbine 26, the fluid will be discharged from theoutlet ports 30 of the turbine into the upper portion of the annularspace 25. It will be appreciated, therefore, that during the operationof the well tool 10, the circulation of the drilling fluid or mud willbe effective for continuously driving the turbine 26 and the generator28 coupled thereto to produce electrical power for operating thedatasignaling means 15.

As depicted in FIG. 3, at least a substantial portion of the mud streamflowing through the annular space 25 enters one or more downwardlyinclined lateral ports 31 formed near the lower end of the inner member22. The fluid entering the ports 31 will then pass through thelongitudinal bore 32 of the inner member and on through the lowerportion of the outer housing 23 therebelow. To produce theaforementioned pressure pulses, the pressure-signaling means 20 includea valve member 33 coaxially mounted within the inner member 22 andadapted for axial movement therein between an elevated position asdepicted in FIG. 3 and a lower port-closing position where the valvemember is co-operatively received within the upper end of a tubularvalve seat 34. As will subsequently be explained, the valve seat 34 isslidably mounted in the inner member 22 and normally retained in itsdepicted elevated position by biasing means such as a compression spring35 supported on an inwardly directed shoulder 36 on the outer housing 23and engaged with the lower end of the valve seat. To support the valvemember 33 for reciprocating movement within the inner member 22, anupright extension or rod 37 is secured to the valve member and extendedupwardly through an annular guide 38 arranged thereabove within theinner member. Biasing means, such as a compression spring 39 compressedbetween the guide 37 and the valve member 33 are operatively arrangedfor urging the valve member downwardly toward its port-closing position.

It will be recognized that so long as the valve member 33 remains in itselevated position depicted in FIG. 3, the drilling fluid can freelycirculate from the annular space 25 through the lateral ports 31 and thetubular valve seat 34 and pass without significant restriction onthrough the lower portion of the outer housing 23 to the drill bit 12the-rebelow. On the other hand, it will be appreciated that once thevalve member 32 is released for downward movement into engagement withthe valve seat 34, the fluid circulation through the fluid ports 31 willbe at least blocked or closed momentarily and produce a correspondingpressure surge or pulse which will be transmitted back up the mud streamin the drill string 11 for detection at the surface.

To releasably retain the valve member 32 in its.elevated position,latching means are provided such as one or more upright leaf springs oryieldable fingers 40 which are secured within the inner member 22 andreleasably coupled to the rod 37 by inwardly directed lugs as at 41 onthe mid-portion of each finger which are adapted to remain engaged underone or more outwardly enlarged shoulders 42 spaced along the upperportion of the elongated rod so long as the fingers are retained intheir respective inwardly contracted positions illustrated in FIG. 3. Toretain the fingers 40 in their latching positions, a solenoid 43 iscoaxially mounted within the inner member 22 and includes a verticallyreciprocating armature 44 carrying a downwardly opening cup-like member45 which is adapted for movement between an elevated position above thelatch fingers and the lower position depicted in FIG. 3 where the cup atleast partially encloses the upper end of the fingers.

In the preferred embodiment illustrated, upwardly directed wedge-shapedheads, as at 46, are mounted on the upper ends of each of the severalfingers 40 and an annular ring 47 is arranged around the cup 45 todefine an internal downwardly directed wedge-like surface 48 which iscomplemental to the opposed surfaces of the wedge-shaped heads. Thus, solong as the cup 45 is disposed over the upright fingers 40, the ring 47will cooperatively engage the wedge-shaped heads 46 to restrain thefingers against moving outwardly from their respective positions shownin FIG. 3. In this manner, so long as the fingers 40 are retained frommoving outwardly, the inwardly directed lugs 41 will be maintained incoengagement under one of the enlarged shoulders 42 on the elongated rod37. It will, therefore, be recognized that the spring 39 is urging thevalve member 33 and the rod 37 downwardly and that it is only thecoaction of the lugs 41 under the shoulder 42 which maintain the valvemember in its elevated position.

On the other hand, as will subsequently be explained in further detail,it will be appreciated that once the solenoid 43 is energized towithdraw the cup 45 from engagement with the enlarged heads 46, thecooperative camming action between the enlarged shoulder 42 and theinwardly directed lugs 41 will be effective for momentarily springingthe fingers 40 outwardly to free the elongated rod 37 and the valvemember 33 for downward movement. Thus, once the solenoid 43 isenergized, the compression spring 39 will be effective for forcefullydriving the valve member 33 downwardly once the enlarged shoulder 42 hasexpanded the midportions of the fingers 40 sufficiently to disengage theenlarged shoulder from the inwardly directed lugs 41.

Accordingly, as depicted in FIG. 4, once the valve member 33 enters thevalve seat 34, the circulating drilling fluid will be momentarily haltedso as to produce a transitory pressure surge or pressure pulse in thenature of a water hammer. Those skilled in the art will, of course,appreciate that the dynamic pressures produced by suchwater hammers arequite substantial. Thus, by virtue of the rapid movement of the valvemember 33 into seating engagement within the valve seat 34, thesubstantial dynamic pressure force which is developed will be imposed onthe upper end 49 of the valve seat and will be effective for urging thevalve seat downwardly in relation to the outer housing 23. In view ofthe substantial magnitude of this pressure force acting on the effectivecross-sectional area of the upper end 49 of the valve seat 34, the valveseat will be shifted downwardly to begin compressing the spring 35.

It will be noted from FIG, 5 that as the valve seat 34 begins movingdownwardly, the valve member 33 will be abruptly halted as an enlargedshoulder 50 on the elongated rod 37 engages the guide 38. Thus, thedynamicpressure force imposed on the upper end 49 of the valve seat 34will be effective for shifting the valve seat away from and out ofengagement with the momentarily halted valve member 33. Moreover, oncethe valve seat 34 is withdrawn from over the valve member 33 as depictedin FIG. 6, a spring 51 arranged between the guide 38 and the shoulder 50will now have been compressed so as to quickly return the valve member33-and the elongated rod 37 upwardly toward their initial elevatedposition.

During this same time interval, it will be noted by comparison of FIGS.5 and 6 that the solenoid 43 has now been de-energized so as toreposition the cup 45 back over the enlarged heads 46 of the latchfingers 40. Thus, once the upper ends 46 of the fingers 40 are againreconfined, it will be appreciated that as the enlarged shoulders 42 onthe elongated rod 37 move upwardly past the inwardly directed lugs 41,the midportions of the fingers will be momentarily cammed outwardly.Then, once one or more of the shoulders 42 are above the lugs 41, the.mid-portions of the fingers 40 will again contract to resecure theelongated rod 37 and the valve member 33 in their elevated positions asdepicted in FIG. 3. Similarly, the downwardly acting dynamic pressureforces acting on the valve seat 34 will be quickly terminated as thevalve member 33 is withdrawn therefrom so that the compression spring 35will rapidly return the valve seat upwardly to its elevated position asillustrated in FIG. 3.

Referring again to FIGS. 1 and 2, once the well tool 10 is in positionwithin the borehole 13 the measuring devices 17 and 18 will function toprovide measurements of the particular conditions which are beingmonitored and cause the measurement encoder 19 to produce the series ofelectrical signals representative of these conditions. Each of thesesignals will, therefore, momentarily energize the solenoid 43 toinitiate the operation of the pressure-signaling means 20 as in FIGS. 3and 4. Thus, each time the solenoid 43 is energized,

the valve member 33 will be released so as to move into seatingengagement within the upper end of the valve seat 34 as shown in FIG. 5.Them as depicted in FIG. 6, the downwardly acting pressure forcesimposed on the impingement surface 49 on the valve seat 34 will carrythe valve seat further downwardly for withdrawing the valve seat fromover the valve member 33 as well as for simultaneously compressing thespring 35. Once the springs 35 and 51 are energized, the valve member 33and the valve seat 34 will be returned to their initial elevatedpositions as depicted in FIG. 3.

To understand the underlying principle of the operation of thepressure-signaling means 20, references should be made to FIG. 4. Atthis'point in the sequence;

the valve member 33 has just moved into the upper end of the valve seat34. This movement will, of course, interrupt the downward flow of thecirculating drilling fluid to produce a substantial positive dynamicpressure which is imposed on the impingement surface 49. At the sametime, the continued flow of the drilling fluid that is then below thevalve member 33 and the valve seat 34 will simultaneously produce areduced pressure in the longitudinal bore 52 below the valve seat. As aresult, a substantial downwardly acting pressure force will be imposedon the upper surface 53 of the valve member 33 to drive it furtherdownwardly into the valve seat 34 until the shoulder engages the guide38 (FIG. 5). It will, of course, be appreciated that a substantialdownwardly acting pressure force is also imposed on the surface 49 whichwill be equal to the pressure differential imposed on the effectivecrosssectional area of the valve seat 34 which will also drive the valveseat downwardly.

As the valve seat 34 is driven downwardly, the spring 35 will, ofcourse, be compressed to develop corresponding upwardly acting springforces tending to return the valve seat to its elevated position. Oncethe valve seat 34 is moved downwardly away from the valve member 33(FIG. 6), the positive pressure in the longitudinal bore 54 above thevalve member 33 will be reduced so as to be equalized with the pressurebelow the valve seat (by way of the space between the valve member andthe valve seat), the spring force provided by the now-compressed spring35 will be effective for driving the valve seat upwardly. This upwardtravel of the valve seat 34 will, therefore, reposition the valve seatin its initial position as the valve member 33 is also returned to itsinitial elevated position by the spring 51.

It will be appreciated, therefore, that each time the solenoid 43 isenergized, the valve member 33 will be released for movement to itsport-closing position and the valve seat 34 will thereafter move tore-establish communication so that a momentary pressure surge will beproduced without unduly retarding the continued circulation of thedrilling fluid. As previously mentioned, the pressure pulses which aresequentially produced by the repetitive closing and opening of the valvemember 33 will be transmitted to the surface by way of the stream ofdrilling fluid being circulated downwardly through the drill string 11.Thus, as these pressure pulses sequentially arrive at the surface, thesurface apparatus 21 will detect them to produce a meaningful recordwhich is indicative of the conditions being monitored by thecondition-responsive devices 17 and 18.

Accordingly, it will be appreciated that the new and improveddata-signaling apparatus of the present invention is particularlyadapted for producing pressure will be operative for employing thecirculating drilling fluid as a motive force for operating the valvemeans and momentarily interrupting the flow of the circulating drillingfluid so as to produce a pressure pulse for transmission to the surface.

While a particular embodiment of the present invention has been shownand described, it is apparent that changes and modifications may be madewithout de parting from this invention in its broader aspects; and,therefore, the aim in the appended claims is to cover all such changesand modifications as fall within the true spirit and scope of thisinvention.

What is claimed is:

1. Apparatus adapted for determining at least one downhole conditionwhile excavating a borehole and comprising: a tubular drill stringhaving a boreholeexcavating device dependently coupled thereto and defining a flow passage for circulating drilling fluids between thesurface and said borehole-excavating device;

data-signaling means on said drill string adapted for producingelectrical signals indicative of at least one downhole condition; andpressure-signaling means on said drill string adapted for developingpressure pulses in drilling fluids flowing through said drill string fortransmission through said flow passage to the surface and includingvalve means adapted for selective movement between first and second openpositions and at least one intermediate closed position between saidopen positions, actuating means operable in response to said electricalsignals for selectively moving said valve means from said first openposition to said closed position for closing said valve means to producesaid pressure pulses, and fluid-responsive means operatively associatedwith said valve means and operable only upon closing of said valve meansfor utilizing said pressure pulses for moving said valve means from saidclosed position to said second open position to reopen said valve means.

2. The apparatus of claim 1 further including means adapted to belocated at the surface and responsive to said pressure pulses forproviding indications of said pressure pulses.

3. The apparatus of claim 2 further including biasing means operableonly upon movement of said valve means to said second open position forreturning said valve means to said first open position to awaitsubsequent electrical signals to said actuating means.

4. The apparatus of claim 1 wherein said actuating means include anelectrical solenoid operatively associated with said valve means tonormally latch said valve means in said first open position and adaptedfor releasing said valve means for movement to said closed position uponenergization of said solenoid by said datasignaling means; and biasingmeans adapted for moving said valve means to said closed position uponenergization of said solenoid to release said valve means.

5. The apparatus of claim 4 further including biasing means operableonly upon movement of said valve means to said second open position forreturning said valve means to said first open position in latchingassociation with said solenoid to await subsequent electrical signals tosaid actuating means.

6. Apparatus adapted for transmitting data to the surface during thedrilling of a borehole and comprising: a body adapted for connection ina tubular drill string and having a flow passage arranged to carrydrilling fluids between the surface and a borehole-drilling devicedependently coupled therebelow; and pressuresignaling means on said bodyand including valve means adapted for cyclical movement between firstand second passage-opening positions and at least onepassage-obstructing position to obstruct the flow of drilling fluidsthrough said flow passage and produce pressure pulses in such fluids fortransmission therethrough to the surface, first means operativelyassociated with said valve means and adapted for moving said valve meansfrom a first passage-opening position to said assage-obstructingposition, valve-operating means selectively responsive to electricalsignals operatively associated with said first means and said valvemeans and adapted for only initiating each operating cycle of said valvemeans, and second means including fluid-responsive means operativelyassociated with said valve means and adapted for utilizing said pressurepulses in said flow passage to move said valve means from saidpassage-obstructing position to a second passage-opening position.

7. The apparatus of claim 6 further including electrical signaling meanson said body coupled to said valveoperating means and adapted forproducing electrical signals representative of at least one downholecondition to repetitively operate said valve-operating means.

8. The apparatus of claim 6 wherein said first means include biasingmeans operative only upon operation of said valve-operating means formoving said valve means to said passage-obstructing position.

9. The apparatus of claim 6 wherein said first means include firstbiasing means operative only upon operation of said valve-operatingmeans for moving said valve means to said passage-obstructing position;and said second means include second biasing means operative only uponmovement of said valve means to said last-mentioned passage-openingposition for returning said valve means to said first-mentionedpassageopening position to await the next electrical signal to saidvalve-operating means.

10. Apparatus adapted for transmitting data to the surface during thedrilling of a borehole and comprising: a body adapted for connection ina tubular drill string and having a flow passage arranged to carrydrilling fluids between the surface and a borehole-drilling devicedependently coupled therebelow; and pressuresignaling means on said bodyand including anannular valve seat movably disposed in said flow passageand adapted for movement therein between first and second spacedpositions, first biasing means normally retaining said valve seat in itssaid first position, a valve member movably disposed on said body andadapted for movement between a non-obstructing position and aflow-obstructing position in said flow passage where said valve memberis received within said valve seat when said valve seat is in its saidfirst position, valveoperating means normally retaining said valvemember in its said non-obstructing position and responsive to electricalsignals for selectively moving said valve member to its saidflow-obstructing position within said valve seat to produce pressurepulses in drilling fluids flowing through said flow passage fortransmission to the surface, means on said valve seat and responsive tosaid pressure pulses for moving said valve seat against said firstbiasing means from its said first position to its said second positionto re-establish unobstructed flow of drilling fluids through said flowpassage after said valve member is moved to its said flow-obstructingposition, and second biasing means adapted for returning said valvemember to its said non-obstructing position to await another electricalsignal.

11. The apparatus of claim 10 further including means in said flowpassage dividing said flow passage into spaced upper and lower portionsand defining at least one port between said positions of said valvemember and communicating said upper and lower portions of said flowpassage so that movement of said valve member to its saidflow-obstructing position within said valve seat will at leastsubstantially block the flow of drilling fluids through said flowpassage to produce said pressure pulses.

12. The apparatus of claim 10 wherein said valveoperating means includethird biasing means normally urging said valve member toward its saidflowobstructing position, latch means releasably retaining said valvemember in its said non-obstructing position, and electrical meansoperatively associated with said latch means and responsive to saidelectrical signals for actuating said latch means to release said valvemember for movement to its said flow-obstructing position.

13. The apparatus of claim 12 further including means in said flowpassage dividing said flow passage into spaced upper and lower portionsand defining at least one port between said positions of said valvemember and communicating said upper and lower portions of said flowpassage so that movement of said valve member to its saidflow-obstructing position within said valve seat will at leastsubstantially block the flow of drilling fluids through said flowpassage to produce said pressure pulses.

14. The apparatus of claim 12 further including electrical signalingmeans on said body coupled to said electrical means and adapted forproducing electrical signals representative of at least one downholecondition to repetitively operate said electrical means.

15. The apparatus of claim 14 wherein said electrical means include anelectrical solenoid operatively associated with said latch means andadapted for actuating said latch means to release said valve member inresponse to said electrical signals by said electrical signaling means.

16. Apparatus adapted for transmitting data to the surface during thedrilling of a borehole and comprising: a tubular drill string having aborehole-drilling device dependently coupled thereto and defining a flowpassage for circulating drilling fluids between the surface and saidborehole-drilling device; data-signaling means on said drill stringadapted for producing electrical signals indicative of at least onedownhole condition; and pressure-signaling means on said drill stringadapted for selectively developing pressure pulses in drilling fluidsflowing through said fluid passage for transmission through said drillstring to the surface and including an annular valve seat movablydisposed in said flow passage and adapted for movement therein betweenfirst and second spaced positions, first biasing means normallyretaining said valve seat in its said first position, a valve membermovably arranged on said drill string and adapted for movement between anonobstructing position and a flow-obstructing position in said flowpassage where said valve member is received within said valve seat whensaid valve seat is in its said first position, valve-operating meansnormally retaining said valve member in its said non-obstructingposition and responsive to electrical signals for selectively movingsaid valve member to its said flow-obstructing position within saidvalve seat to produce pressure pulses in drilling fluids flowing throughsaid flow passage for transmission to the surface, means on said valveseat and responsive to said pressure pulses for moving said' valve seatagainst said first biasing means from its said first position to itssaid second position to re-establish unobstructed flow of drillingfluids through said flow passage after said valve member is moved to itssaid flow-obstructing position, and second biasing means adapted forreturning said valve member to its said non-obstructing position toawait another electrical signal.

17. The apparatus of claim 16 further including means adapted to belocated at the surface and responsive to said pressure pulses forproviding indications of said pressure pulses.

18. The apparatus of claim 12 wherein said valveoperating means includethird biasing means normally urging said valve member toward its saidflowobstructing position, latch means releasably retaining said valvemember in its said non-obstructing position, and electrical meansoperatively associated with said latch means and responsive to saidelectrical signals for actuating said latch means to release said valvemember for movement to its said flow-obstructing position.

19. The apparatus of claim 18 wherein said electrical means include anelectrical solenoid operatively associated with said latch means andadapted for actuating said latch means to release said valve member inresponse to said electrical signals by said data-signaling

1. Apparatus adapted for determining at least one downhole conditionwhile excavating a borehole and comprising: a tubular drill stringhaving a borehole-excavating device dependently coupled thereto anddefining a flow passage for circulating drilling fluids between thesurface and said borehole-excavating device; data-signaling means onsaid drill string adapted for producing electrical signals indicative ofat least one downhole condition; and pressure-signaling means on saiddrill string adapted for developing pressure pulses in drilling fluidsflowing through said drill string for transmission through said flowpassage to the surface and including valve means adapted for selectivemovement between first and second open positions and at least oneintermediate closed position between said open positions, actuatingmeans operable in response to said electrical signals for selectivelymoving said valve means from said first open position to said closedposition for closing said valve means to produce said pressure pulses,and fluid-responsive means operatively associated with said valve meansand operable only upon closing of said valve means for utilizing saidpressure pulses for moving said valve means from said closed position tosaid second open position to reopen said valve means.
 2. The apparatusof claim 1 further including means adapted to be located at the surfaceand responsive to said pressure pulses for providing indications of saidpressure pulses.
 3. The apparatus of claim 2 further including biasingmeans operable only upon movement of said valve means to said secondopen position for returning said valve means to said first open positionto await subsequent electrical signals to said actuating means.
 4. Theapparatus of claim 1 wherein said actuating means include an electricalsolenoid operatively associated with said valve means to normally latchsaid valve means in said first open position and adapted for releasingsaid valve means for movement to said closed position upon energizationof said solenoid by said data-signaling means; and biasing means adaptedfor moving said valve means to said closed position upon energization ofsaid solenoid to release said valve means.
 5. The apparatus of claim 4further including biasing means operable only upon movement of saidvalve means to said second open position for returning said valve meansto said first open position in latching association with said solenoidto await subsequent electrical signals to said actuating means. 6.Apparatus adapted for transmitting data to the surface during thedrilling of a borehole and comprising: a body adapted for connection ina tubular drill string and having a flow passage arranged to carrydrilling fluids between the surface and a borehole-drilling devicedependently coupled therebelow; and pressure-signaling means on saidbody and including valve means adapted for cyclical movement betweenfirst and second passage-opening positions and at least onepassage-obstructing position to obstruct the flow of drilling fluidsthrough said flow passage and produce pressure pulses in such fluids fortransmission therethrough to the surface, first means operativelyassociated with said valve means and adapted for moving said valve meansfrom a first passage-opening position to said passage-obstructingposition, valve-operating means selectively responsive to electricalsignals operatively associated with said first means and said valvemeans and adapted for only initiating each operating cycle of said valvemeans, and second means including fluid-responsive means operativelyassociated with said valve means and adapted for utilizing said pressurepulses in said flow passage to move said valve means from saidpassage-obstructing position to a second passage-opening position. 7.The apparatus of claim 6 further including electrical signaling means onsaid body coupled to said valve-operating means and adapted forproducing electrical signals representative of at least one downholecondition to repetitively operate said valve-operating means.
 8. Theapparatus of clAim 6 wherein said first means include biasing meansoperative only upon operation of said valve-operating means for movingsaid valve means to said passage-obstructing position.
 9. The apparatusof claim 6 wherein said first means include first biasing meansoperative only upon operation of said valve-operating means for movingsaid valve means to said passage-obstructing position; and said secondmeans include second biasing means operative only upon movement of saidvalve means to said last-mentioned passage-opening position forreturning said valve means to said first-mentioned passage-openingposition to await the next electrical signal to said valve-operatingmeans.
 10. Apparatus adapted for transmitting data to the surface duringthe drilling of a borehole and comprising: a body adapted for connectionin a tubular drill string and having a flow passage arranged to carrydrilling fluids between the surface and a borehole-drilling devicedependently coupled therebelow; and pressure-signaling means on saidbody and including an annular valve seat movably disposed in said flowpassage and adapted for movement therein between first and second spacedpositions, first biasing means normally retaining said valve seat in itssaid first position, a valve member movably disposed on said body andadapted for movement between a non-obstructing position and aflow-obstructing position in said flow passage where said valve memberis received within said valve seat when said valve seat is in its saidfirst position, valve-operating means normally retaining said valvemember in its said non-obstructing position and responsive to electricalsignals for selectively moving said valve member to its saidflow-obstructing position within said valve seat to produce pressurepulses in drilling fluids flowing through said flow passage fortransmission to the surface, means on said valve seat and responsive tosaid pressure pulses for moving said valve seat against said firstbiasing means from its said first position to its said second positionto re-establish unobstructed flow of drilling fluids through said flowpassage after said valve member is moved to its said flow-obstructingposition, and second biasing means adapted for returning said valvemember to its said non-obstructing position to await another electricalsignal.
 11. The apparatus of claim 10 further including means in saidflow passage dividing said flow passage into spaced upper and lowerportions and defining at least one port between said positions of saidvalve member and communicating said upper and lower portions of saidflow passage so that movement of said valve member to its saidflow-obstructing position within said valve seat will at leastsubstantially block the flow of drilling fluids through said flowpassage to produce said pressure pulses.
 12. The apparatus of claim 10wherein said valve-operating means include third biasing means normallyurging said valve member toward its said flow-obstructing position,latch means releasably retaining said valve member in its saidnon-obstructing position, and electrical means operatively associatedwith said latch means and responsive to said electrical signals foractuating said latch means to release said valve member for movement toits said flow-obstructing position.
 13. The apparatus of claim 12further including means in said flow passage dividing said flow passageinto spaced upper and lower portions and defining at least one portbetween said positions of said valve member and communicating said upperand lower portions of said flow passage so that movement of said valvemember to its said flow-obstructing position within said valve seat willat least substantially block the flow of drilling fluids through saidflow passage to produce said pressure pulses.
 14. The apparatus of claim12 further including electrical signaling means on said body coupled tosaid electrical means and adapted for producing electrical signalsrepresentative of at least onE downhole condition to repetitivelyoperate said electrical means.
 15. The apparatus of claim 14 whereinsaid electrical means include an electrical solenoid operativelyassociated with said latch means and adapted for actuating said latchmeans to release said valve member in response to said electricalsignals by said electrical signaling means.
 16. Apparatus adapted fortransmitting data to the surface during the drilling of a borehole andcomprising: a tubular drill string having a borehole-drilling devicedependently coupled thereto and defining a flow passage for circulatingdrilling fluids between the surface and said borehole-drilling device;data-signaling means on said drill string adapted for producingelectrical signals indicative of at least one downhole condition; andpressure-signaling means on said drill string adapted for selectivelydeveloping pressure pulses in drilling fluids flowing through said fluidpassage for transmission through said drill string to the surface andincluding an annular valve seat movably disposed in said flow passageand adapted for movement therein between first and second spacedpositions, first biasing means normally retaining said valve seat in itssaid first position, a valve member movably arranged on said drillstring and adapted for movement between a non-obstructing position and aflow-obstructing position in said flow passage where said valve memberis received within said valve seat when said valve seat is in its saidfirst position, valve-operating means normally retaining said valvemember in its said non-obstructing position and responsive to electricalsignals for selectively moving said valve member to its saidflow-obstructing position within said valve seat to produce pressurepulses in drilling fluids flowing through said flow passage fortransmission to the surface, means on said valve seat and responsive tosaid pressure pulses for moving said valve seat against said firstbiasing means from its said first position to its said second positionto re-establish unobstructed flow of drilling fluids through said flowpassage after said valve member is moved to its said flow-obstructingposition, and second biasing means adapted for returning said valvemember to its said non-obstructing position to await another electricalsignal.
 17. The apparatus of claim 16 further including means adapted tobe located at the surface and responsive to said pressure pulses forproviding indications of said pressure pulses.
 18. The apparatus ofclaim 12 wherein said valve-operating means include third biasing meansnormally urging said valve member toward its said flow-obstructingposition, latch means releasably retaining said valve member in its saidnon-obstructing position, and electrical means operatively associatedwith said latch means and responsive to said electrical signals foractuating said latch means to release said valve member for movement toits said flow-obstructing position.
 19. The apparatus of claim 18wherein said electrical means include an electrical solenoid operativelyassociated with said latch means and adapted for actuating said latchmeans to release said valve member in response to said electricalsignals by said data-signaling means.